Last visit was: 13 Dec 2024, 03:33 It is currently 13 Dec 2024, 03:33
Close
GMAT Club Daily Prep
Thank you for using the timer - this advanced tool can estimate your performance and suggest more practice questions. We have subscribed you to Daily Prep Questions via email.

Customized
for You

we will pick new questions that match your level based on your Timer History

Track
Your Progress

every week, we’ll send you an estimated GMAT score based on your performance

Practice
Pays

we will pick new questions that match your level based on your Timer History
Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.
Close
Request Expert Reply
Confirm Cancel
User avatar
innocous
Joined: 13 May 2013
Last visit: 20 Jun 2021
Posts: 16
Own Kudos:
145
 []
Given Kudos: 7
Posts: 16
Kudos: 145
 []
Kudos
Add Kudos
17
Bookmarks
Bookmark this Post
User avatar
blueseas
User avatar
Current Student
Joined: 14 Dec 2012
Last visit: 15 Jan 2019
Posts: 577
Own Kudos:
4,393
 []
Given Kudos: 197
Location: India
Concentration: General Management, Operations
GMAT 1: 700 Q50 V34
GPA: 3.6
GMAT 1: 700 Q50 V34
Posts: 577
Kudos: 4,393
 []
1
Kudos
Add Kudos
Bookmarks
Bookmark this Post
avatar
zerosleep
Joined: 15 Aug 2013
Last visit: 01 Jul 2017
Posts: 42
Own Kudos:
Given Kudos: 7
Posts: 42
Kudos: 124
Kudos
Add Kudos
Bookmarks
Bookmark this Post
avatar
faamir
Joined: 14 May 2014
Last visit: 29 Jun 2018
Posts: 11
Own Kudos:
Given Kudos: 54
GMAT 1: 760 Q50 V42
GMAT 1: 760 Q50 V42
Posts: 11
Kudos: 23
Kudos
Add Kudos
Bookmarks
Bookmark this Post
zerosleep
In the xy-plane , line l intersects a circle with center at origin.Is the slope of line l equal to zero?

1) line l passes through second quadrant.
2) line l is perpendicular to the tangent of the circle.

FS1: Line l passing through second quadrant and intersecting the circle can be either parall to x-axis(in which case its slope is 0) or not parallel to x-axis(slope not eual to 0). Hence insufficient.
FS2: Line which is perpendicular to the tangent must pass thought centre (since angle betwwen radius and point of contact of tangent to a circle is 90 degrees). Hence, the line can have multiple possibilities for its slope (including 0 and infinity when the line is parallel to x or y axis respectively). Not sufficient.

Combining the above two, the only possibility is when the slope is negatice but not zero (x-axis is not in II quadrant). Hence slope iof line l is not zero for any case.
Sufficient. So answer should be C.


The 2nd statement does not imply that the line l has to pass through the tangent point. It could be any parallel line perpendicular to the tangent.
Shouldn't the answer be E?

Please clarify??
User avatar
Bunuel
User avatar
Math Expert
Joined: 02 Sep 2009
Last visit: 13 Dec 2024
Posts: 97,865
Own Kudos:
685,466
 []
Given Kudos: 88,266
Products:
Expert reply
Active GMAT Club Expert! Tag them with @ followed by their username for a faster response.
Posts: 97,865
Kudos: 685,466
 []
1
Kudos
Add Kudos
1
Bookmarks
Bookmark this Post
faamir
zerosleep
In the xy-plane , line l intersects a circle with center at origin.Is the slope of line l equal to zero?

1) line l passes through second quadrant.
2) line l is perpendicular to the tangent of the circle.

FS1: Line l passing through second quadrant and intersecting the circle can be either parall to x-axis(in which case its slope is 0) or not parallel to x-axis(slope not eual to 0). Hence insufficient.
FS2: Line which is perpendicular to the tangent must pass thought centre (since angle betwwen radius and point of contact of tangent to a circle is 90 degrees). Hence, the line can have multiple possibilities for its slope (including 0 and infinity when the line is parallel to x or y axis respectively). Not sufficient.

Combining the above two, the only possibility is when the slope is negatice but not zero (x-axis is not in II quadrant). Hence slope iof line l is not zero for any case.
Sufficient. So answer should be C.


The 2nd statement does not imply that the line l has to pass through the tangent point. It could be any parallel line perpendicular to the tangent.
Shouldn't the answer be E?

Please clarify??

You are right the answer must be E:
Attachment:
Untitled.png
Untitled.png [ 26.48 KiB | Viewed 7433 times ]
avatar
faamir
Joined: 14 May 2014
Last visit: 29 Jun 2018
Posts: 11
Own Kudos:
Given Kudos: 54
GMAT 1: 760 Q50 V42
GMAT 1: 760 Q50 V42
Posts: 11
Kudos: 23
Kudos
Add Kudos
Bookmarks
Bookmark this Post
Bunuel,

Thank you so much for the quick response. You are the best :D
avatar
salaxzar
Joined: 08 Jun 2011
Last visit: 10 Jul 2017
Posts: 16
Own Kudos:
29
 []
Given Kudos: 11
Posts: 16
Kudos: 29
 []
1
Kudos
Add Kudos
Bookmarks
Bookmark this Post
Stmt1: If any line l passes through second quadrant and intersects the circle, then it can be
- either parallel to x-axis => slope is 0
- or not parallel to x-axis => slope not equal to 0.
Hence insufficient.

Stmt2: If a line is perpendicular to the tangent must pass thought centre (since angle between radius and point of contact of tangent to a circle is 90 degrees). Hence, the line can have multiple possibilities for its slope (including 0 and infinity when the line is parallel to x or y axis respectively). SO this is also Not sufficient.

If we combine two stmts, the only possibility left is negative slope but not zero (x-axis is not in II quadrant). Hence slope of line will never be 0.
Sufficient. Ans- C.
User avatar
BrentGMATPrepNow
User avatar
GMAT Club Legend
Joined: 12 Sep 2015
Last visit: 13 May 2024
Posts: 6,786
Own Kudos:
32,192
 []
Given Kudos: 799
Location: Canada
Expert reply
Posts: 6,786
Kudos: 32,192
 []
Kudos
Add Kudos
1
Bookmarks
Bookmark this Post
innocous
In the xy-plane, line l intersects a circle with center at origin. Is the slope of line l equal to zero?

(1) Line l passes through second quadrant.

(2) Line l is perpendicular to the tangent of the circle.

Target question: Is the slope of line l equal to zero?

IMPORTANT: Since a circle can have an infinite number of tangent lines, the answer here is E.
To prove this, let's jump straight to . . .

Statements 1 and 2 combined
Here are two possible scenarios that meet the two given conditions:
Case a:


Case b:


In once case, the slope of line l equals 0, and in the other case, the slope of line l does not equal 0.
Since we cannot answer the target question with certainty, the combined statements are NOT SUFFICIENT

Answer: E

Cheers,
Brent
User avatar
bumpbot
User avatar
Non-Human User
Joined: 09 Sep 2013
Last visit: 04 Jan 2021
Posts: 35,803
Own Kudos:
Posts: 35,803
Kudos: 929
Kudos
Add Kudos
Bookmarks
Bookmark this Post
Hello from the GMAT Club BumpBot!

Thanks to another GMAT Club member, I have just discovered this valuable topic, yet it had no discussion for over a year. I am now bumping it up - doing my job. I think you may find it valuable (esp those replies with Kudos).

Want to see all other topics I dig out? Follow me (click follow button on profile). You will receive a summary of all topics I bump in your profile area as well as via email.
Moderator:
Math Expert
97864 posts